The unit of measure em is calculated on the selector’s parent element. Therefore ul li is 1.8 times the base font and ul li em is 3.24 times the base element, because it’s 1.8 * 1.8 (ul li’s font-size).

To solve this, you can either use rem, which is based on the root element (so, the html or body font-size), or you can set ul li e to 1em.